Thiosugar silver halide solubilizing agents



1955 w. J. HUMPHLETT ETAL 3,220,838

THIOSUGAR SILVER HALIDE SOLUBILIZING AGENTS Filed March 19, 1963 V/SC'OUS PROCE S S/N 6 COMPOSITION SILVER HAL/0E EMULSION FIG , sup/ am 22 LVER HAL/0E EMULSION LAYER FIG 2 2/ NUCLEATED RECEPTION LAYER SUPPORT v /RECE/V//VG SHEET sup/=0 NUOLEATED RECEPTION LAYER POD OON 7'A/N/N6 V/SOOUS VJ PROCESS/N6 COMPOS/ 7' I ON BI LD- S/LVER HAL/DE EMULSION LAYER i SUPPOR r SILVER HAL/DE 44 EMULSION LAYER 43 SUPPORT FOR FILM SPOOL 4/ NUCLEATED RECEPTION LAYER WEB SUPPORT W/LBERT J. HUMPHLETI GRANT M. l-lA/ST JAMES R. KING INVENTORS BY Q .fMfllyfi A TTORNEYS United States Patent 3,220,838 TIHGSUGAR SILVER HALHDE SGLUBELHZING AGENTS Wilbert J. Humphlett, Grant M. Haist, and James R. King,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Mar. 19, 1963, Ser. No. 266,338 14 Claims. (Cl. 96-29) The present invention relates to novel silver halide solubilizing agents.

Developed photographic silver halide emulsion layers are fixed or stabilized by a chemical treatment in order to produce a permanent silver image. If the residual silver halide is left in the developed emulsion layer, it would be converted to silver upon exposure to light and thus obliterate the image. To avoid this, developed photographic silver halide emulsion layers are commonly fixed by using a fixing agent which forms a Water-soluble complex which is then washed out of the emulsion layer along with the fixing agent. Such fixing agents as a class are silver halide solubilizing materials.

Silver halide solubilizing materials are also utilized in chemical transfer processes wherein unexposed and undeveloped silver halide is transferred to a receiving sheet or a web, the solubilizing agent facilitating the transfer of such silver halide.

Silver halide solubilizing agents also have utility in socalled monobaths wherein a single processing solution can be utilized to both develop and fix a photographic silver halide emulsion layer.

It is an object of this invention to provide novel compositions having high silver halide solvent activity.

It is another object of this invention to provide novel fixing compositions for developed photographic silver halide emulsion layers.

It is another object of this invention to provide a novel process for fixing developed photographic silver halide emulsion layers.

It is another object of this invention to provide novel monobath compositions.

It is another object of this invention to provide novel monobath compositions that can be used under elevated temperature conditions without objectionable sludge format-ion.

It is also an object of this invention to provide a photographic chemical transfer process wherein a novel silver halide solvent is utilized.

In addition, it is an object of this invention to provide a new viscous processing composition suitable for use in photographic pods of the type utilized with rapid incamera processing films and the like.

Similarly, it is an object of this invention to provide a novel viscous processing composition suitable for use with photographic webs of the type utilized in the rapid processing of motion picture film and the like.

These and other objects of the invention are accomplished with compositions containing silver halide solubilizing thiosugar compounds having the general formula:

(CHOHL:

(CHOEDm GH OH ice wherein X is a hydrogen atom or a methanol radical (CH OH), n is an integer of 0-1 and m is an integer of 0-3.

The subject silver halide solubilizing agents or thiosugars can be prepared by reacting thiocyanic acid with a sugar such as D-glucose, allose, talose, altrose, D-galactose, D-xylose, ribose, lyxose, L-a'rabinose, fructose, D- rnanno-L-fructo-octose [1. Am. Chem. Soc., 72, 1345 (1950)], D-erythro-L-n1anno-nonulose [J Am. Chem. Soc., 77, 3096 (1955)], L-manno-heptulose [1. Am. Chem. Soc., 73, 730 (1951)], and the like sugars including geometric or stero isomers thereof, in accordance with procedures previously described in the art. Reference is made to Berichte Chemie, 69, 748 (1936); Berichte Chemie, 71, 590 (1938); J. Chem. Soc. 1954, 2644; and J. Org. Chem. 10, 267 (1945) for methods for preparing the present thiosugars. Typical preferred thiosuga'rs used in the invention include 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione; 4,5 1,2-D-galactofurano -2-oxazolidinethione; (4,5-) 1,2-D-galactofurano)-2-oxazolidinethione; 4, 5-(1,2-L-arabinofurano)-2-oxazolidinethione; 4,5-(1,2-D- xylofurano)-2-oxazolidinethione and the like.

The subject thiosugar silver halide solubilizing agents are typically utilized in aqueous compositions containing at least about 3 grams of thiosugar per liter of composition. However, the amount of such silver halide solubilizing agents utilized can be widely varied, the amount used being readily ascertainable by one skilled in the art for the particular photographic application. Generally, however, the amount of thiosugar utilized would vary between about 3 grams and 200 grams per liter of processing composition. When the subject thiosugars are utilized in baths for clearing or fixing developed photographic film, at least 5 or 10 to 200 grams of thiosugar per liter of processing solution .are more generally utilized to obtain fixing within a practical time interval. Lower concentrations, down to about 3 grams of the subject thiosugars per liter are more generally utilized as the silver halide solvent in chemical transfer processes.

The subject thiosugars exhibits fixing or clearing activity in alkaline or basic solutions. We more generally utilize our thiosugars in alkaline solutions having pHs of at least about 8 or 9, although the alkalinity of processing compositions can be widely varied in accordance with usual practice. Such alkaline materials as alkali metal carbonates and hydroxides and amines can be utilized to acquire the desired alkalinity.

Monobaths which can be utilized to both develop and fix an exposed photographic silver halide emulsion are well known in the art. Such monobaths contain both a photographic developing agent suitable for developing or reducing latent silver halide images to silver and a silver halide solubilizing or fixing agent such as sodium thiosulfate. We have found that our thiosugars can be utilized in lieu of the conventional sodium thiosulfate and the like silver halide solubilizing agents in such monobath compositions. Typical silver halide developing agents that can be employed in monobath compositions include such hydroquinonyl compounds as hydroquinone, N-methyl-paminophenolsulfate, chlorohydroquinone, 2,4-diaminophenol and 3,4-diaminophenol hydrochloride; 3-pyrazolidones such as l-phenyl-3-pyrazolidone, 4-methyl-l-phenyl- 3-pyrazolidone and 1-phenyl-4,4-dimet hyl-3-pyrazolidone; ene-dioles such as ascorbic acid; catechol; pyrogallol; gallic acid; p-phenylene diamines; and the like, as well as mixtures of such developing agents.

Monobaths of the invention that have high viscosity are particularly useful processing compositions. High viscosity monobath compositions are desirable as they can be readily spread in a uniform layer on the film to be processed. Such compositions desirably have viscosities in excess of about 500 centipoises at a temperature of approximately 24 C. and preferably of the order of 1000 to 20,000 centipoises at this temperature. A wide variety of thickening agents can be added to monobath compositions to impart high viscosities. Such viscosity-imparting materials are film-forming materials that retain this property and their viscosity in aqueous alkaline solution. Suitable viscosity-increasing materials include sodium carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol, sodium salts of polymethacrylic acid and polyacrylic acid, and the like.

The subject. thiosugars have particular utility as silver halide solvents in photographic chemical transfer processes. Such transfer processes are well known in the art. Rott in US. Patent 2,352,014 described such a transfer process for preparing reversal images. In the Rott process an exposed photographic silver halide emulsion is impregnated with a developer and pressed in contact with a receiving sheet in the presence of a silver halide solvent and a fogging agent. The undeveloped silver halide in the emulsion layer is transferred by means of the silver halide solvent to the receiving sheet, this transferred silver halide developing to silver to form a positive image on the receiving sheet. Other investigators in this field, such as Land, suggested the use of various specific fogging agents or nuclei that could be used in the reception layer to facilitate the formation of a silver image therein and the use of viscous processing materials to facilitate the utilization of processing materials in pods positioned between the light-sensitive negative layer and the reception layer. Reference is made to such Land patents as US. Patents 2,543,181, 2,584,029 and 2,698,236 for suitable photographic silver halide transfer processes in which the present silver halide solvents can be effectively utilized.

A wide variety of nuclei or silver halide precipitating agents can be utilized in the reception layers used in silver halide solvent transfer processes. Such nuclei are incorporated into conventional photographic organic hydrophilic colloid layers and include such physical nuclei or chemical precipitants as:

(a) heavy metals, especially in colloidal form and salts of these metals,

(b) salts, the anions of which form silver salts less soluble than the silver halide of the photographic emulsion to be processed, and

(c) nondilfusing polymeric materials with functional groups capable of combining with and in solubilizing silver ions.

Typical useful silver precipitating agents include sulfides, selenides, polysulfides, polyselenides, thiourea and its derivatives, mercaptans, stannous halides, silver, gold, platinum, palladium, mercury, colloidal silver, aminoguanidine sulfate, aminoguanidine carbonate, arsenous oxide, sodium stannite, substituted hydrazines, zanthates, and the like. Polyvinyl mercaptoacetate is an example of a suitable nonditfusing polymeric silver precipitant. Heavy metal sulfides such as lead, silver, zinc, aluminum, cadmium and bismuth sulfides are useful, particularly the sulfides of lead and zinc alone or in an admixture, or complex salts of these with thioacetamide, dithio-oxamide or dithio-biuret. The heavy metals and the noble metals particularly in colloidal form are especially effective. Other silver precipitating agents will occur to those skilled in the present art.

Such silver precipitating or nucleating agents can be utilized in reception layers that are separate elements from the light-sensitive silver halide negative element being processed, or they can be utilized as reception layers integral with the light-sensitive negative element. When the reception layer is utilized as a separate element, the reception layer is typically in the form of a web imbibed with processing material of the type suitable for processing long units of film such as motion picture film, or in the form of a support for receiving positive images of the ,snapshot type that are processed in accordance with the Land 4 patents referred to above. Belgian Patent 472,243 and Tregillus et al., US. Serial No. 835,473 filed August 24, 1959 describe typical solvent transfer processes utilizing webs as a silver halide reception means. When the reception layer is integral with the light-sensitive negative element, such reception layer is generally a sublayer over which is coated the silver halide in a vehicle that is readily removable during processing such as a hydrophilic colloid soluble in aqueous alkali like cellulose ether phthalate.

FIGS. 1 to 4 illustrate fragmentary views in sectional elevation of typical light-sensitive elements that can be processed in accordance with the invention as well as typical processing methods of the invention utilizing the present thiosugars as silver halide solubilizing agents.

FIG. 1 illustrates a typical light-sensitive element comprising support 10 having coated thereon silver halide emulsion layer 11, The above-described monobath compositions containing both a developing agent and a thiosugar of the invention thickened to a high viscosity with a thickening material can be spread on the surface of layer 11 as illustrated by viscous composition 12 in the drawings. After the processing period, the viscous processing composition thereafter is typically removed from the silver halide emulsion layer by wiping, squeegeeing or by washing.

FIG. 2 of the drawings illustrates a typical light-sensitive element having an integral nucleated reception layer that can be utilized to prepare positive images without the necessity of a separate image receiving sheet. On support 20 is coated nucleated reception layer 21 which is typically an organic hydrophilic colloid material such as hardened gelatin containing any of the nucleating agents described above. Over layer 21 is coated silver halide emulsion layer 22 comprising silver halide dispersed in a substrate that can be readily removed during or after processing. Preferred substrates for layer 22 are materials that are soluble in aqueous alkali such as cellulose ether phthalate. In the processing of a light-sensitive element of the type illustrated in FIG. 2, a latent image is formed in silver halide emulsion layer 22 on exposure. The resulting exposed element can thereafter be treated with a monobath composition of the type described above either by immersing the element in a solution of the monobath or by coating the surface of the element with a viscous monobath processing composition, such monobaths containing the present thiosugar silver halide solubilizing agents. During processing, a silver negative image is developed in silver halide emulsion layer 22 and unexposed and undeveloped silver halide in this emulsion layer is transferred to nucleated reception layer 21. In the nucleated reception layer, the transferred silver halide develops to form a positive silver image. Silver halide emulsion layer 22 containing the negative silver image is removed either during the course of the processing by the aqueous alkaline processing composition or by subsequently washing off.

FIG. 3 of the drawings illustrates a typical light-sensitive negative element and a sheet for receiving images transferred from the negative element. Also included in FIG. 3 is a pod containing a viscous processing composition positioned between the light-sensitive negative element and the receiving sheet. In FIG. 3 on support 30 is coated silver halide emulsion layer 31 which serves as the light-sensitive negative element or film material. The receiving sheet comprises support 35 having coated thereon nucleated reception layer 34. Typical nucleating agents are described in detail hereinabove. Positioned between the receiving sheet and the light-sensitive negative element is pod 31 containing viscous processing composition 32. Viscous processing composition 32 can be any of the viscous monobaths described above. After exposure of the light-sensitive negative element, a latent image is formed in layer 31. Processing of this light sensitive element is effected by drawing the sandwiched layers illustrated in FIG. 3 through rollers to rupture pod 33 and spread a uniform layer of viscous processing composition 32 between silver halide emulsion layer 31 and nucleated reception layer 34. The latent negative image is developed to silver in layer 31 and remaining unexposed and undeveloped silver halide in layer 31 is transferred to nucleated reception layer 34 wherein it is developed to form a positive silver image. On separation of the receiving sheet from the light-sensitive negative element, a positive silver image remains on the receiving sheet. Such a chemical transfer process has particular utility for rapid in-camera processing applications.

FIG. 4 of the drawings illustrates a typical processing web spooled or sandwiched with a photographic film to be processed. The processing web comprises web support 40 having coated thereon nucleated reception layer 41. The nucleated reception layer comprises an organic hydrophilic substrate having therein development nuclei of the type described above. The photographic film to be processed comprises support 43 having coated thereon silver halide emulsion layer 44. The web and the photographic film are sandwiched together so that nucleated reception layer 41 of the web is in intimate contact with silver halide emulsion layer 44 of the film on spool 42. Prior to spooling together the web and the film to be processed, a monobath processing composition including a thiosugar of the invention as a silver halide solvent is imbibed onto the web. The web and the film are left in the sandwiched or wound form on spool 42 until the processing of the silver halide emulsion layer is complete. Thereafter, the film and the web are unwound resulting in a fully processed negative film. In the processing of the film with the web containing a monobath composition, a negative silver image is formed in silver halide emulsion layer 44 corresponding to regions of exposure, and unexposed and undeveloped silver halide in this layer is transferred to nucleated reception layer 42 and developed to silver. Such web processing techniques have particular utility for processing strips of film such as microfilm and motion picture film up to 100 feet or more in length.

We have found that the subject thiosugars, as a class of silver solubilizing agents, have many superior properties over currently-used agents for this purpose. In general, the subject thiosugars do not have the strong characteristic odors which characterize many of the conventional sulfurcontaining fixing agents, such as thioglycerol, mercaptoacetic acid, diethylaminoethanethiol and others. The present fixing agents produce silver images having colder image tones than conventional fixing agents. Further, emulsions fixed with the preesnt thiosugars exhibit improved detail in shadow areas and desirable light edge effects. Also, the subject fixing agents can be utilized with a wide range of temperature conditions. A compound consisting of the 2-oxazolidinethione nucleus of the present compounds was found not to possess silver halide solubilizing properties.

The following examples further illustrate the present invention.

EXAMPLE 1 A high-speed, negative-type, developing-out, coarsegrain, gelatino-silver bromoiodide emulsion coated on a cellulose acetate film support was exposed in an intensity scale sensitometer and immersed for 8- minutes at 75 F. with intermittent agitation in the following monobath composition:

1-phenyl-3-pyrazolidone g 6 Hydroquinone g 8 Sodium sulfite, anhydrous g 50 Z-diethylaminoethanol ml 80 4,5-(1,2-D-xylofurano)-2-oxazolidinethione g 15 Water to make 1 liter.

Thereafter the resulting film was washed in water and dried in air. The density-log exposure curve of the resulting processed film was similar to that given for the same film developed for 8 minutes at 68 F. in Kodak D-76 developer, fixed for 10 minutes in Kodak F-S fixer, and washed in water. Reference is made to Handbook of Chemistry and Physics, 30th Edition, Chemical Rubber Publishing Company, Cleveland, Ohio, pages 2543 and 2570, for the formulations of Kodak D-76 developer and Kodak F-5 fixer.

EXAMPLE 2 A high-speed, negative-type, developing-out, coarsegrain, gelatino-silver bromoiodide emulsion coated on a cellulose acetate film support was exposed in an intensity scale sen-sitometer and processed for 8 minutes at 75 F. using intemittent agitation in the following monobath composition 1-phenyl-3-pyrazolidone g 4 Hydroquinone g 12 Sodium sulfite, anhydrous g 50 2-diethylaminoethanol ml 80 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione g 20 Water to make 1 liter.

The resulting processed film was washed in water and then dried in air. The density-log exposure curve for the processed film was similar to that for the same exposed film developed for 8 minutes at 68 F. in Kodak D-76 developer fixed for 10 minutes in Kodak F-5 fixer, and washed in water.

EXAMPLE 3 Clearing Time (Sec.)

Thiosugar Carbonate Hydroxide 4,5-(1,Z-D-Xylofurano)-2roxazolidinethione 47 71 4,5 (1,2-L-Arabinofurano) -2-oxazolidinethione 44 81 4,5- (1,2-D- Glucofurano) -2-oxazolidinethione- 67 88 4,5-(1,2-D-Galaetoturano)-2-oxazol.idinethione 55 90 4,5- (2,3D-Fruetopyrano) -2-oxaz0lidinethione 68 80 N0 clearing or removal of silver halide took place when the thiosugar addenda were not utilized in the various test alkaline media. The data set out in the above table illustrate that a wide variety of thiosugars of the inven tion can be utilized as silver halide solvents. When 0.25 mole of 2-oxazolidinethione was substituted for the thiosugars in the alkaline solutions, no fixing or clearing of the film strips occurred.

EXAMPLE 4 The subject thiosugars can be used as silver halide solvents in viscous monobath compositions used in diffusion transfer processes wherein unexposed silver halide in the negative or taking element is transferred to a nucleated receiving sheet with the aid of the subject thiosugars. The following processing composition was prepared:

Sodium sulfite, anhydrous g 10.0 Sodium carbonate monohydrate g 35.0 4-methyl-l-phenyl-S-pyrazolidone g 1.2 Potassium hydroxide, 45% solution cc 4.0 Sodium isoascorbate g 40. 4,5- (2,3-D-fructopyrano)-2-oxazolidinethione g 10.0

7 Potassium'iodide, 0.1% solution cc 50.0 Potassium bromide ..g 2.0 Hydroxyethylcellulose g 10.0

Water to make 1 liter.

The viscosity of the above composition was 2500 c.p.s. as measured on a Brookfield Synchro-Lectric viscometer Model LVF, using a No. 2 spindle at 6 rpm. Pods were prepared for the above processing composition from aluminum foil lined with polyethylene. Several 10 ml. portions of the processing composition were heat-sealed into the pods. A negative film was prepared comprising a high-speed, coarse-grain, negative-type, developing-out, gelatino-silver bromoiodide emulsion on a cellulose acetate film support. A receiving sheet comprising a whitecolored cellulose acetate film support having coated thereon a gelatin layer containing nickel sulfide nuclei was prepared. Processing was carried out by positioning a pod containing the processing composition between the receiving sheet and the negative film as illustrated by FIG. 3 in the drawings. The resulting sandwich was then pulled between rollers to rupture the pod and spread a uniform layer of processing solution between the negative film and the receiving sheet. The layers of the sandwich were left in contact for 2 minutes at 75 F. On separation of the receiving sheet and the negative film, a positive silver image was present on the receiving sheet.

EXAMPLE 5 The subject thiosugars can also be utilized in viscous monobath processing compositions as silver halide solvents in processes not utilizing silver halide reception ele- Water to make 500 ml.

Composition A was added to Composition B with vigorous agitation until a uniformly thickened solution was obtained. Thereafter 0.2 g. of Carey Lea silver was uniformly dispersed in the prepared processing solution. The viscosity of the resulting processing solution was about 6500 c.p.s. when measured using a Brookfield LVT Model Viscometer with a No. 2 spindle at 6 r.p.m. at 70 F. The prepared viscous processing composition was used to process a light-sensitive film comprising a high-speed, coarse-grain, negative-type, developing-out, gelatino-silver bromoiodide emulsion on a cellulose acetate film base. The film was exposed in an intensity scale sensitometer and a layer of the viscous processing composition was spread over the emulsion surface of the film as illustrated in FIG. 1 in the drawings. After 10 minutes at 70 F., the processing composition was squeegeed from the film. A fully processed film having a light and heat stable negative silver image resulted. Unexposed silver halide was removed during the processing.

EXAMPLE 6 The thiosugars of the invention can also be used as silver halide solubilizing agents in producing direct-positive images without the aid of a separate receiving sheet or element. A light-sensitive photographic film of the type illustrated by FIG. 2 in the drawings was prepared by coating on a transparent cellulose acetate base a sublayer of hardened gelatin containing zinc sulfide nuclei. Over the resulting layer was coated a high-speed, coarse- 8 grain, negative-type, developing-out emulsion of silver bromoiodide in an alkali-soluble cellulose ether phthalate substrated. The resulting film was exposed in an intensity scale sensitometer and thereafter processed for 4 minutes at 20 C. in the following processing composition.

G. Ethylenediaminetetraacetic acid 1 Sodium sulfite, anhydrous 75 Sodium hydroxide 12 Hydroquinone 15 4-methyl-l-phenyl-3-pyrazolidone 1 Potassium bromide 1 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione 5 Water to make 1 liter.

During the processing of the exposed film, a negative silver image Was developed in the silver halide cellulose ether phthalate layer. Unexposed and undeveloped silver halide in this layer was dissolved by the thiosugar solubilizing agent in the processing composition and transferred to the hardened gelatin zinc sulfide nuclei-containing underlayer wherein the silver halide developed or was reduced to silver to form a positive silver image. As the cellulose ether phthalate is soluble in aqueous alkali, the cellulose ether phthalate containing the negative silver layer was readily washed away leaving a positive silver image.

EXAMPLE 7 The following processing composition was prepared:

N-methyl-p-aminophenol sulfate 1.5 Hydroquinone 2.5 Sodium sulfite, anhydrous 60.0 Trisodium phosphate 40.0 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione 10.0

Water to make 1 liter.

The above processing composition was used to process a fine-grain, negative-type, developing-out, gelatino-silver bromoiodide emulsion layer on a cellulose acetate film support that had been exposed in an intensity scale sensitometer. The exposed film was immered for about 30 seconds in the processing solution and then pressed in contact with a receiving sheet comprising a cellulose acetate film support having coated thereon a gelatin layer containing nickel sulfide nuclei. After 60 seconds at 70 F., the receiving sheet and the negative filmswere stripped apart and a positive dense brown-black silver image was found on the receiver.

EXAMPLE 8 A high-speed, coarse-grain, negative-type, developingout, gelatino-silver bromoiodide emulsion coated on a cellulose acetate film support was exposed in an intensity scale sensitometer and thereafter processed with the following composition:

G. 4-methyl-1-phenyl-3-pyrazolidone 2 Sodium sulfite, anhydrous 30 Sodium erythorbate 30 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione 70 Water to make 1 liter. (Adjusted to pH of 11.5 with sodium hydroxide.)

The above processing composition was spread on the surface of the exposed photographic element at F. A negative was produced in 7 seconds that had dense image areas and was uneifected by heat, light, or moisture. The processing composition was squeegeed from the surface of the film. No washing was necessary to effect the image stability. The subject thio sugars can be used in monobaths at high temperatures as they donot cause silver precipitation or sludge as do conventional fixing baths containing sodium thiosulfate. Monobaths containing sodium thiosulfate sludge quickly at temperatures of 100 to F.

9 EXAMPLE 9 An aqueous solution of 65 g. per liter of 4,5-(2,3-D- fructopyrano)-2-oxazolidinethione adjusted to a pH of 12.5 with potassium hydroxide was used to process a coarse-grain, high-speed, negative-type, developing-out, gelatino-silver bromoiodide emulsion containing 4-phenylcatechol. The film was exposed in an intensity scale sensitometer. The processing was effected by immersing a sample of the film in the processing solution for about 8 minutes at 75 F. Thereafter, the resulting developed and fixed film was Washed with water. The film has a silver negative image having dense image areas, clean background areas, and is unetfected by heat, light, and moisture after processing.

EXAMPLE 10 EXAMPLE 1 l The subject thiosugar silver halide solubilizing agents can be utilized in monob-aths which are imbibed on processing webs used to develop and fix silver halide emulsion layers. A typical suitable processing composition has the following formulation:

l-phenyl-3-pyrazolidone l Hydroquinone 10 2 dimethylaminoethanolsulfate (20 mole percent 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione 10 Potassium bromide 2 Water to make 1 liter.

A processing web is prepared by coating on a cellulose acetate support a layer comprising 2 g. of gelatin and 8 mg. of Carey Lea silver per square foot. This web is soaked for about minutes in the monobath processing composition described above prior to winding or coiling in contact with the film to be processed in the manner illustrated in FIG. 4 of the drawings. A high-speed, coarsegrain, negative-type, developing-out, gelatino-silver bromoiodide emulsion coated on a cellulose acetate film support that has been exposed is processed by bringing the silver halide emulsion layer of the film in intimate contact with the nucleated layer of the soaked web and by allowing the resulting rolled sandwich to be maintained for minutes at 75 F. Thereafter, the web and the film are peeled away to leave a fully developed and fixed negative film having a negative silver image in the exposed areas and being cleared of silver halide in the unexposed areas. Similar results can be obtained by utilizing a web prepared from a cellulose acetate film base that had been surfaced-hydrolyzed in a sodium hydroxide aqueous ethanol solution for about one hour and thereafter soaked for about 3 minutes in a 0.1% gold chloride solution followed by a 3-minute soak in a 0.2% solution of N-methylp-aminophenolsulfate to form metallic gold nuclei in the hydrolyzed cellulose acetate.

EXAMPLE 12.PREPARATION OF THIOSUGARS A single-necked, wide-mouthed, 22-liter, round flask is charged with 8.64 kg. (48 moles) of fructose, 4.8 kg. (49.4 moles) of potassium thiocyanate and 1.92 liters of water. A viscous solution is made by warming to 40- 60 C. on a Glas-Col heating mantle with occasional stirring. The flask is placed in a hood in an ice-brine bath and equipped for mechanical stirring with a 5-inch Teflon paddle connected to a glass shaft. To the stirred solution cooled to 20 C., there is added in portions, over 20-40 minutes, 4.8 liters (57.7 moles) of concentrated hydrochloric acid. During the addition, the temperature of the reaction mixture is maintained at 2025 C. by adding small pieces of Dy-Ice as necessary. Potassium chloride gradually precipitates. When the addition is complete, the reaction mixture is stirred for 30 minutes longer with ice-bath cooling. The slightly colored mixture is let stand overnight without stirring. By morning, some solids mixed with potassium chloride separate. 4 kg. of crushed ice is added, and the suspension is stirred in an ice bath for 2 hours. When the ice in the flask has melted, the remaining solids are removed by suction filtration. An enamel tray is nearly fil led with the filtrate from the preparation and placed in a powerful draft in a nearly closed hood. After 3 to 4 days, When an almost-solid mush results, the crude product is cut out in chunks and placed in two 22-liter round flasks. To each flask is added 4 liters of water with brief stirring. After standing overnight, the dark supernatent liquor is carefully decanted. Water is again added, stirred, let settle, and decanted. The crude product is suction-filtered in a 10 gal. porcelain Knight filter over several hours. This product is washed four times with 2 liters of water and then with 2 liters of acetone to facilitate drying. The product is air-dried and ground to a powder. In a typical preparation from 16.35 kg. of fructose, 5.5 kg. (28 percent yield of 4,5-(2,3-D-fructopyrano)-2-0xazolidinethione) was obtained, M.P. 183 C. (dec.),

Ef (243 m :930 in methanol Other thiosugars of the invention can be similarly prepared by substituting the sugars described hereinabove for the fructose.

The invention has been described in considerable detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims We claim:

1. A photograpic chemical transfer method for processing an image-exposed silver halide emulsion layer which comprises developing said silver halide to produce a negative silver image, treating with resulting developed silver halide emulsion layer with an aqueous alkaline composition, transferring unexposed and undeveloped silver halide to a reception layer containing a silver halide precipitating agent, and reducing the said transferred silver halide to silver, said aqueous alkaline composition containing at least about 3 grams per liter of said composition of a silver halide solubilizing agent having the formula HOI-Dm HQOH wherein X is selected from the group consisting of a hydrogen atom and a methanol radical, n is an integer of 0 to 1 and m is an integer of 0 to 3.

2. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams per 1 1 liter of said composition of a silver halide solubilizing agent having the formula wherein X is selected from the group consisting of a hydrogen atom and a methanol radical, n is an integer of to 1 and m is an integer of 0 to 3.

3. An aqueous alkaline composition containing a silver halide developing agent and at least about 3 grams per liter of said composition of a silver halide solubilizing agent having the formula (C IHOIDm CHzOH wherein X is selected from the group consisting of a hydrogen atom and a methanol radical, n is an integer of of 0 to 1 and m is an integer of 0 to 3.

4. An aqueous alkaline photographic monobath composition having a viscosity of at least about 500 centipoises at 24 C. and being suitable for both developing and fixing photographic silver halide emulsions comprising a photographic silver halide developing agent and at least about 3 grams per liter of said composition of a silver halide solubilizing agent having the formula in claim 4 wherein hydroxyethylcellulose is used as a viscosity increasing addendum.

7. An aqueous alkaline photographic monobath composition suitable for both developing and fixing photographic silver halide emulsions comprising a 3-pyrazo1idone photographic silver halide developing agent and about 3 to 200 grams of 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione per liter of said monobath composition.

8. An aqueous alkaline photographic monobath composition suitable for both developing and fixing photographic silver halide emulsions comprising a 3-pyrazolidone photographic silver halide developing agent and about 3 to 200 grams of 4,5-(1,l-xylofurano)-2-oxaboli-.

dinethione per liter of said monobath composition.

9. An aqueous alkaline photographic monobath composition having a viscosity of about 1000 to 200,000 centipoises at 24 C. and being suitable for both developing and fixing photographic silver halide emulsions comprising a photographic silver halide developing agent selected from the group consisting of 1-phenyl-3-pyrazolidone, 4-methyl-1-phenyl-3-pyrazolidone and 1-phenyl-4,4 dimethyl-3-pyrazolidone, hydroxyethylcellulose as a viscosity increasing addendum, and about 3 to 200 grams of 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione per liter of said monobath composition as a silver halide solubilizing addendum.

10. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams of 4,5- (1,2-D-xylofurano)-2-oxazolidinethione per liter of said composition.

11. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams of 4,5- (1,Z-L-arabinofurano)-2-oxazolidinethione per liter of said composition.

12. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams of 4,5-(1,Z-D-glucofurano)-2-oxaz0lidinethione per liter of said composition.

13. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams of 4,5- (1,2-D-galactofurano)-2-oxazolidinethione per liter of said composition.

14. The process for solubilizing unexposed and undeveloped silver halide on a photographic element which comprises treating said silver halide with an aqueous alkaline composition comprising at least about 3 grams of 4,5-(2,3-D-fructopyrano)-2-oxazolidinethione per liter of said composition.

References Cited by the Examiner Berichte Chemie 69, 1936, pp. 748-754. J. Org. Chemistry, 10, 1945, pp. 267-276.

NORMAN G. TORCHIN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,220,838 November 30, 1965 Wilbert J. Humphlett et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 12, line 13, for "4,5-[1,1xy10furano) 2- xaboli-" read 4,5[1,2xy10furano)2-0xazoli- (SEAL) Attest:

ERNEST W. SW IDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

1. A PHOTOGRAPHIC CHEMICAL TRANSFER METHOD FOR PROCESSING AN IMAGE-EXPOSED SILVER HALIDE EMULSION LAYER WHICH COMPRISES DEVELOPING SAID SILVER HALIDE TO PRODUCE A NEGATIVE SILVER IMAGE, TREATING WITH RESULTING DEVELOPED SILVER HALIDE EMULSION LAYER WITH AN AQUEOUS ALKALINE COMPOSITION, TRANSFERRING UNEXPOSED AND UNDEVELOPED SILVER HALIDE TO A RECEPTION LAYER CONTAINING A SILVER HALIDE PRECIPITATING AGENT, AND REDUCING THE SAID TRANSFERRED SILVER HALIDE TO SILVER, SAID AQUEOUS ALKALINE COMPOSITION CONTAINING AT LEAST ABOUT 3 GRAMS PER LITER OF SAID COMPOSITION OF A SILVER HALIDE SOLUBILIZING AGENT HAVING THE FORMULA 